The invention relates to methods and systems for sensing comprising one or more radio frequency components.
Generally, manufacturing processes in pharmaceutical and biological fields utilize various disposables or single use items, such as polymeric pouches or bags, tubing, valves, for holding and transferring product in various stages. Such bags are often used to make, store and/or distribute a single batch of drugs, and/or to store a batch of drugs or other material until the batch is ready to be dispensed into vials or bottles for distribution or further storage, or may be dispensed directly into further manufacturing and processing equipment. These bags and disposables generally need to be sterilized, for example using ionizing radiation, such as gamma radiation, prior to use.
Typically, sensors are coupled to such bags to acquire information regarding various environmental parameters in the bags, such as temperature, pressure, pH, oxygen, carbon dioxide, etc. These sensors may also use radio frequency identification (RFID) tags. Conventionally, radio frequency identification (RFID) tags are used for asset tracking. For example, RFID tags may be used for tracking the removal of objects from a location and the replacement of the objects at the location. The RFID tags have been combined with a biometric reader. Such RFID circuit uses certain functional blocks for processing both the biometric signals and the RFID signals. Each RFID tag has a unique factory programmed chip identification (ID) number. These unique numbers are read to relate the RFID tag to the article to which the tag is attached. RFID tags are also used for detecting the unauthorized opening of containers and baggage. RFID tags can be included in a variety of articles such as postage stamps and other mailing labels, garments, and numerous other articles.
However, in certain applications, such as those in which the tag is required to be subjected to radiation, the environment may corrupt or destroy the digital data contents in the memory within the tag. While RFID tags have been known and have been adapted to various uses, such as inventory control and theft protection of items, the RFID tags have been unsuitable for bio bags or disposable items that are gamma radiated for sterilization.
When subjected to radiation, specifically gamma radiation, the contents of the memory elements of the RFID tags can be lost or corrupted resulting in the undesirable alteration of associated data stored therein. However, there are a number of applications, such as, but not limited to, pharmaceutical industry, where irradiation of the system is a requirement to provide an adequate sterilization.
After exposure to gamma irradiation, the device employing the RFID tag apparently continues to function, however, there is an unintended but noticeable and undesirable variation in the performance of the device. For example, corruption of device results in data corruption, which refers to errors or alterations in data that occur during data retrieval, introducing unintended and undesirable changes to the original data. Adverse affects may result in data loss from the electronic device. As used herein, the term “data loss” refers to unrecoverable data unavailability due to hardware or software failure. On the material level, FRAM (Ferroelectric Random Access Memory) is relatively more gamma radiation resistant than EEPROM (Electrically Erasable Programmable Read-Only Memory). However, FRAM also experiences gamma-irradiation effects. The energy of gamma radiation is high enough to potentially cause the displacement damage in the ferroelectric material. For example, after an exposure to a gamma radiation, FRAM experiences the decrease in retained polarization charge due to an alteration of the switching characteristics of the ferroelectric due to changes in the internal fields. This radiation-induced degradation of the switching characteristics of the ferroelectric is due to transport and trapping near the electrodes of radiation-induced charge in the ferroelectric material. Once trapped, the charge can alter the local field around the dipoles, altering the switching characteristics as a function of applied voltage. Depending on the fabrication method of FRAM (for example, sputtering, sol-gel deposition, spin-on deposition, metal-organic chemical vapor deposition, liquid source misted chemical deposition), the trap sites may be at grain boundaries or in distributed defects in the ferroelectric material. In addition to the charge trapping, gamma radiation can also directly alter the polarizability of individual dipoles or domains.
On the device level, the FRAM memory chip of the RFID tag consists of a standard electric CMOS circuitry and an array of ferroelectric capacitors in which the polarization dipoles are oriented during the memory write operation of the FRAM. Radiation damage in CMOS includes, but is not limited to the threshold voltage shift, increased leakage currents, and short-circuit latchup.
Devices that are gamma irradiated, such as in pharmaceutical components, bioprocess industry, and other applications cannot utilize reliably read-write RFID tags such as EEPROM and FRAM tags. Thus, products used in these environments must find alternative solutions or improve existing memory components. For example, in some cases, a simple optical barcode is affixed to the article, and a database is used to store and retrieve the pertinent information associated with that barcode. While this allows the data associated with the article to be retrieved, new data cannot be directly written to the barcode. Instead, it requires a database access, often through a wireless network. An access to the network often can be impossible or unacceptable at certain, yet critical times, for example during process start-up. Thus, critical article manufacturing information (e.g. electronic pedigree) and current end-user information (e.g. start-up conditions) should be stored directly in the memory of the RFID tag attached to the article. Further, when the RFID tag is attached to the article, such local information in the memory of the tag provides the ability for the authentication of the article.
Therefore, it would be desirable to have sensors that could withstand radiation without data loss or corruption.